Force/velocity and power/velocity relationships in squat exercise

Area of Science:

• Biomechanics
• Sports Science
• Exercise Physiology

Background:

• Understanding the force-velocity and power-velocity relationships is crucial for optimizing athletic performance.
• Previous research has primarily focused on isolated muscle actions rather than complex, multi-joint exercises like the squat.

Purpose of the Study:

• To characterize the force/velocity and power/velocity relationships during maximal dynamic squat exercises.
• To compare extrapolated maximal force (F0) with directly measured isometric force.
• To investigate the influence of varying loads on these biomechanical parameters.

Main Methods:

• Fifteen elite downhill skiers performed maximal dynamic squats with loads from 60-180 kg and isometric squats.
• Force and velocity data were collected using a guided barbell and force platform.
• Force/velocity and power/velocity relationships were analyzed, and maximal force (F0) and maximal power (Wmax) were extrapolated.

Main Results:

• A linear force/velocity relationship was observed in all subjects (r2 = 0.83-0.98).
• Extrapolated F0 was significantly higher (23%) than measured isometric force and uncorrelated, possibly due to differing movement angles.
• A parabolic power/velocity relationship was found (r2 = 0.94-0.99), with peak power occurring at the lightest load (60 kg).

Conclusions:

• The squat exercise demonstrates distinct force/velocity and power/velocity characteristics compared to isolated movements.
• The discrepancy between extrapolated and measured isometric force highlights the importance of movement range in force production.
• Maximal power likely occurs at higher velocities than those studied, suggesting optimal training loads may be lighter than typically assumed.